Radiation-induced segregation is well known in metals, but has been rarely studied in ceramics. We discover that radiation can induce notable segregation of one of the constituent elements to grain boundaries in a ceramic, despite the fact that the ceramic forms a line compound and therefore has a strong thermodynamic driving force to resist off-stoichiometry. Specifically, irradiation of silicon carbide at 300 °C leads to carbon enrichment near grain boundaries, whereas the enrichment diminishes for irradiation at 600 °C. The temperature dependence of this radiation-induced segregation is different from that shown in metallic systems. Using an ab initio informed rate theory model, we demonstrate that this difference is introduced by the unique defect energy landscapes present in the covalent system. Additionally, we discover that grain boundaries in unirradiated silicon carbide grown by chemical vapour deposition are intrinsically carbon-depleted. The inherent grain boundary chemistry and its evolution under radiation are both critical for understanding the many properties of ceramics associated with grain boundaries.

辐射引起的偏析在金属中是众所周知的，但很少在陶瓷中研究。我们发现，尽管陶瓷形成线化合物并因此具有强大的热力学驱动力来抵抗化学计量失调，但辐射仍可导致陶瓷中的一种构成元素明显地偏向晶界。具体地，在300℃下照射碳化硅导致晶界附近的碳富集，而在600℃下照射时该富集减少。这种辐射引起的偏析的温度依赖性不同于金属体系中显示的依赖性。使用从头算的率理论模型，我们证明了这种差异是由共价体系中存在的独特缺陷能态引起的。另外，我们发现通过化学气相沉积生长的未辐照碳化硅中的晶界本质上是贫碳的。固有的晶界化学及其在辐射下的演化对于理解与晶界有关的陶瓷的许多特性都是至关重要的。